remove flink-metrics dependencies (#24)

Author: ravisingal

platform-metrics/build.gradle.kts

@@ -13,8 +13,6 @@ dependencies {
   api("com.typesafe:config:1.4.1")
   api("io.dropwizard.metrics:metrics-core:4.1.16")
   api("io.micrometer:micrometer-core:1.5.3")
-  api("org.apache.flink:flink-metrics-core:1.10.1")
-  api("org.apache.flink:flink-metrics-prometheus_2.12:1.10.1")
   api("javax.servlet:javax.servlet-api:3.1.0")
 
   implementation("io.micrometer:micrometer-registry-prometheus:1.5.3")

platform-metrics/src/main/java/org/hypertrace/core/serviceframework/metrics/MetricsServlet.java

@@ -20,6 +20,9 @@ dependencies {
   implementation("io.dropwizard.metrics:metrics-servlets:4.1.16")
   implementation("org.eclipse.jetty:jetty-servlet:9.4.35.v20201120")
 
+  // Use for metrics servlet
+  implementation("io.prometheus:simpleclient_servlet:0.6.0")
+
   // http client
   implementation("org.apache.httpcomponents:httpclient:4.5.13")
 

platform-metrics/src/main/java/org/hypertrace/core/serviceframework/metrics/flink/PrometheusReporter.java

@@ -14,7 +14,7 @@
 import org.hypertrace.core.serviceframework.spi.PlatformServiceLifecycle.State;
 import org.hypertrace.core.serviceframework.config.ConfigClient;
 import org.hypertrace.core.serviceframework.config.ConfigClientFactory;
-import org.hypertrace.core.serviceframework.metrics.MetricsServlet;
+import io.prometheus.client.exporter.MetricsServlet;
 import org.hypertrace.core.serviceframework.metrics.PlatformMetricsRegistry;
 import org.hypertrace.core.serviceframework.service.servlets.HealthCheckServlet;
 import org.hypertrace.core.serviceframework.service.servlets.JVMDiagnosticServlet;